Reject redundant entries in supported_applications.txt (#438)
Reject redundant entries in supported_applications.txt (#438)

* Reject redundant entries in supported_applications.txt

Raise a test failure if the same application appears more than once in supported_applications.txt. This is to prevent the situation that https://github.com/GoogleCloudPlatform/ops-agent/pull/432 is fixing from reoccurring.
GoogleCloudPlatform/ops-agent,GoogleCloudPlatform/ops-agent